1. Field of the Invention
This invention relates to motor vehicles and more particularly to modified manual synchronized transmissions having special utility in connection with certain classes of racing cars.
2. Description of the Prior Art
Motor vehicles all require transmission systems and there are a wide range of such systems ranging from manual through fully automatic. However, racing cars present particular problems vis-a-vis transmissions due to "class" requirements imposed by various associations which set up rules and guidelines for such cars. For example, in certain classes, there is a requirement that the car be able to move forward and in reverse under its own power, unassisted by handlers or pit crew. In other classes this requirement applies only to forward motion and there is no requirement for a reverse gear.
This performance specification or requirement can, of course, be met by a wide variety of transmissions. However, in order to do so, there must be present gearing which has no utility other than meeting the specification since, once a racing car is in motion, it may best be driven in a fully locked-up configuration where there is, in effect, a direct coupling of engine output to transmission drive shaft. Consequently, conventional methods of meeting the requirement involve heavy transmissions and the utilization of a conventional flywheel. These mechanisms, once the car is moving, represent extra baggage which, deleteriously, effects racing performance.
Commonly used transmissions for modification in accordance with the invention are those known as fully synchronized 3-speed manual transmissions. These may be, for example, of the Chevrolet type (e.g. Muncie) or of the Ford type. While such transmissions are generally similar, there are minor differences involving first and reverse gearing. But all of them involve the selective sliding longitudinal displacement of a sleeve or collar from one gear engaging position to another with, in the case of low gear (i.e. first) and reverse, an intermediate disengaged position. As used henceforth herein, synchronizer is intended to mean such a prior art mechanism and collar is intended to mean that portion thereof which is moved by the forks to cause selective predetermined gear engagement. The collar itself, as in the case of the reverse and first gear collar of the Ford transmission, may be part of a gear train.
A general understanding of the operation of such synchromesh transmissions can be obtained by reference to pages 104 and 105 of "The Bosch Book of the Motor Car" by John Day et al, St. Martin's Press, Inc., NYC (copyright 1975 by Robert Bosch Ltd.).
As used herein, the term modification or the term modified manual transmission is utilized in two senses. In one sense, an actual physical modification of an existing transmission is contemplated. In the other sense, a modification of the design of an existing type of transmission is contemplated. In the first case, there are certain constraints deriving from the need for utilizing as many of the original components as possible. These constraints do not apply in the second case where all components, including housing, can be fabricated ab initio to suit the modified design. Both concepts are intended to be embodied herein since they differ only in the amount of investment one is willing to make in tooling and changes in components which are unrelated to the gravamen of the invention.
I am not aware of prior art solutions to the racing car class requirements discussed above. In retrospect, it has been discovered that there are some mechanisms in the tractor art which permit the vehicles to "Creep" forward or in reverse. One such mechanism is shown in U.S. Pat. No. 4,373,409. However, a separate creeper gear mechanism is utilized which is positioned upstream of the transmission and is independent of it. Further, there is no teaching of modifications within the transmission itself which, by their utilization, would enable a racing car to meet performance specifications.